1. Field of the Invention
The present invention relates to the field of photography and, more specifically, to an improved photographic apparatus for coupling together sheet elements of a self-developing film unit and facilitating the presentation of the coupled sheet elements to the entry of a self-developing film unit process.
2. Description of the Prior Art
Certain types of self-developing film units of the diffusion transfer type, especially large format units such as 8.times.10 black and white or color or x-ray film units, are intentionally designed to have separate image recording and image receiving sheet elements. The image recording or photosensitive film sheet is placed in a cassette which is mounted on the back of a conventional or x-ray camera for exposure. Thereafter, the exposed film sheet is adapted to be located in superposed relation with the image recording or print sheet and coupled thereto in registered facing relation. The coupled sheets are then fed through a pair of pressure applying rollers in a processor which ruptures a pod containing a fluid processing composition and effects the distribution of the fluid between the superposed sheets for development and diffusion transfer. The two sheets are then peeled apart to reveal the positive print on the print sheet.
One system for effecting sheet coupling following exposure is disclosed in U.S. Pat. No. 4,019,194 issued to Norman Cutler on Apr. 19, 1977. In this system, the film sheet has a leader attached to its forward end and includes a forwardly projecting coupling tab thereon. The print sheet includes a leader having a tab receiving slot therein. The cassette includes an extra compartment for receiving the print sheet after film exposure. Once the print sheet is inserted into the cassette, the user manually inserts the tab through the slot on the print sheet to bring the two sheets into coupled relation. The cassette is then inserted into the entry of a commercially available processor for advancement through a pair of pressure rollers.
A more complex system is disclosed in commonly assigned copending application U.S. Ser. No. 957,294 filed by Loring Mills on Nov. 2, 1978. In this system, film and print sheets are bulk loaded into separate cassettes and the apparatus includes a rather complex sheet advancing system for mechanically bringing the film and print sheets into coupling relation for presentment to the processor rollers.
Perhaps more relevant to the present invention is the system disclosed in a commonly assigned copending application U.S. Ser. No. 841,888 filed by Herman Erikson on Oct. 13, 1977, now U.S. Pat. No. 4,156,568. In this system, an apparatus for coupling together sheet elements of the self-developing film unit and presenting them to the entry of a processor is provided in the form of an accessory or adapter for a commercially available large format processor of the type disclosed in the previously noted U.S. Pat. No. 4,019,194. The adapter fits into the entry of the processor and includes a tray for receiving the print sheet therein. The cassette is then inserted into the adapter and, as it approaches its fully inserted position over the print sheet in the tray a guide mechanism guides the film sheet coupling tab into a tab guide passageway between a flap of the print leader and the top surface of the pod of processing fluid. The tab advances along this passageway and through a tab receiving slot at the leading edge or fold line of the print leader. This system eliminates the manual loading of a print into the cassette yet it is not as complex as the mechanized system disclosed in the abovenoted application U.S. Ser. No. 957,294.
It will be noted, however, in this last mentioned system that the trailing end of the pod extends outwardly beyond the flap is not secured to the leader. Therefore, there is the possibility that the coupling tab may pass under the pod rather than over it and follow a path of travel toward the slot which is blocked by the leading end of the pod where it is secured to the print leader. Also, the flap over the top of the pod is in close proximity thereto and the guide means must be very accurate to insure tab insertion into the very narrow tab guide passageway. Therefore, it may be difficult to properly guide the tab into this passageway toward the slot if the film leader and tab have been distorted or mishandled prior to the coupling operation. This system also includes a print sheet hold back device in the form of a pair of spring fingers that prevent or restrain forward movement of the print sheet until it has been coupled with the film sheet. However, the hold back fingers are released by the engagement of the forwardly moving coupled sheet elements and may tend to lose their flex over a period of time and become ineffective.
Therefore, it is an object of the present invention to provide an improved photographic apparatus for coupling together sheet elements of a self-developing film unit and for facilitating the presentation of the coupled sheet elements to the entry of a processing unit wherein the improvement includes some means for lifting the flap away from the top surface of the pod to increase the dimensions of the tab guide passageway so that tab insertion through the slot becomes a less precise and critical operation.
It is yet another object of the invention to provide such an improved photographic apparatus that includes some means for covering the trailing end of the pod to block passage of the film tab thereunder which would preclude accomplishing the coupling function.
Another object of the invention is to provide such an improved apparatus having a hold back device that is moved from a blocking position to an unblocking position in response to engagement by a cassette as it approaches its fully inserted position in the apparatus rather than having the coupled sheets engage and displace a hold back device.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.